Standardization of Squat Test in Study of the Posture in Athletes.

Introduction Background: the squat is a multi-articular movement used in physical training, in different sport techniques (Kellis 2005, Sleivert, 2004, Split 2004, Wilson, 1989, Hay, 1983), and in recovery therapy (Dionisio, 2006). the postural compensation in the body chain were studied in weightlifting (Neto junior, 2004; Hoozemans, 1999), in low back pain (Chow, 2005), and in fastigued subjects (Nardone, 1997, Johnston, 1998; Vuillerme, 2001, Derave, 2001 - 2002). Objectives: The aim of this study was to design a quantitative protocol for the analysis of the squat-test (Cuzzolin, 2005). The protocol aims at identifying affections, resulting in postural alterations. Description: The squat-test is performed at different arm positions, meant to create different limitations on the postural chain. During the execution of each position of unloaded squat, the 3D total-body kinematics and the ground reactions (GFR) at the two feet are acquired. the alterations in the dynamics and kinematics of the squat, in particular in the symmetry and fluency of the execution, indicate affections of the musculo-skeletal system. Methods: 6 elite male handball players were analyzed in 5 testing conditions (5 arm position). Three repetitions were acquired for each testing condition. For each repetition, the knee ranged form full extension to 60° of flexion and back, and the feet were kept at 30° of external rotation. Each subject was tested in both non-fatigued and fatigued conditions. The £D kinematics was acquired using stereophotogrammetry (SMART,BTS, Milan Italy), and the GRF were synchronously acquired by means of 2 force plates (Bertec, Ohio, USA). The kinematics of the head, trunk, arms, pelvis, thighs, shanks, and feet were reconstructed using che CAST protocol (Cappozzo et al, 1995). Results: 3 main indicators for the normal execution were identified: 1) the range in the total COP rate along the anterior-posterior (AP) and medio-lateral (ML) directions; 2) the smoothness of the COP trajectory (AP vs MP); 3) the shape of the AP COP trajectory vs knee flexion angle. These indicators allow a screening for altered conditions, the analytical data are used for the identification of the specific muscolo-skeletal alterations. Conclusion: The proposed analysis of the squat-test is elegible for the screening of athletes for the identification of alterations at the musculo-skeletal system. Future analysis of large samples of pathological athletes is planned to identify specific pathological conditions.